Studies of Ionic Current Rectification Using Polyethyleneimines Coated Glass Nanopipettes

Abstract

The modification of glass nanopipettes with polyethyleneimines (PEIs) has been successfully achieved by a relatively simple method, and the smallest tip opening is around 3 nm. Thus, in a much wider range of glass pipettes with radii from several nanometers to a few micrometers, the ion current rectification (ICR) phenomenon has been observed. The influences of different KCl concentrations, pH values, and tip radii on the ICR are investigated in detail. The sizes of PEIs have been determined by dynamic light scattering, and the effect of the sizes of PEIs for the modification, especially for a few nanometer-pipettes in radii, is also discussed. These findings systemically confirm and complement the theoretical model and provide a platform for possible selectively molecular detection and mimic biological ion channels.

A Multiparameter pH‐Sensitive Nanodevice Based on Plasmonic Nanopores

“…The orifice of its pulled end can be precisely controlled down to 50 nm. [12] With its macrosized intact end, the nanopipette can be easily handled and connected with electrophysiological or microinjection setups. [13] The structural property of nanopipette enables it to be conveniently put into the desired microspace with the help of a 3D microcontroller.…”

Ionic Current Rectification in Organic Solutions with Quartz Nanopipettes

“…In addition, many others have modified the surface of pipettes to explore the ICR phenomenon with different types of polymers, such as polylysine, 23 poly(acrylic acid), 24 chitosan, 25 and polymine. 26 Currently, almost all of the studies about ICR have been carried out in aqueous solutions, and mostly using KCl as the electrolyte; 26 only a few solvents other than water have been involved. Yusko et al 27 and White et al 35 added dimethyl sulfoxide (DMSO) into KCl solution to change the conductance of the solution, which caused the liquid-phase negative differential resistance to appear.…”

Ion current rectification effect of porous graphene membrane

“…4(A) and (B), the I-V curves obtained from the pores in G/PET stack and PET membrane with KCl concentration from 0.002 to 0.008 mol/L, respectively. All of non-linear I-V curves indicate that the conical shape nanochannels can rectify the ion current while flowing through them because the surface charge density of conical pore is asymmetrically distributed along the nanochannel [13] and the diameter of the tip opening is in proper relationship with the thickness of the electrical double layer extending from the pore wall [14]. The ion-current rectification phenomenon can be described by defining "on" and "off" states for the nanochannel rectifier [13].…”

“…For example, the alumina/silicon dioxide hetero-structured solid state nanopore membrane was used to study the rectification effect at relatively high electrolyte concentrations and the rectification coefficient was in the range of 1 to 7 [17]. The glass nanopipettes were modified with polyethyleneimines (PEIs) and the related ion current rectification was studied [14]. The dependence of ion current rectification on tip radius of nanopipettes for PEIs-coated pipettes was obtained and the maximum rectification coefficient of 25 happened when the pore size in the range of 1 µm.…”